In the state of the art, in order for the drive power transmitted to the driving wheels of the rail vehicle to be compatible with the adhesion of said wheels, the motive power unit of the vehicle is generally provided with adhesion monitoring apparatus.
Such apparatus conventionally comprises a power control stage for the motor of the motive power unit, and an adhesion monitoring stage which proivides the power control stage with a reference signal that is generated on the basis of at least one operating characteristic of the motor, so as to keep under control, i.e. so as to reduce or even eliminate, wheel spin on the motive power unit.
Such apparatus makes it possible to reduce or even eliminate any commencement of wheel spin, in particular when the vehicle starts moving.
Unfortunately, such apparatus suffers from drawbacks, in particular because it can enable the wheels to slip too much on the rail and give rise to momentary loss of adhesion.
An object of the invention is to mitigate that drawback.
To this end, the invention provides monitoring apparatus for monitoring the adhesion of a motive power unit of an electric rail vehicle set, which apparatus comprises a power control stage for controlling the power supplied to the motor of the motive power unit, an adhesion monitoring stage for delivering to the power control stage a reference signal generated on the basis of at least a first operating characteristic of the motor so as to keep the slip of the wheels of the motive power unit under control, and further comprising means for generating an activation signal for activating the monitoring apparatus and means for injecting the activation signal into the reference signal so as to cause it to deliver a modified reference signal, wherein said means for generating the activation signal include means for measuring a second operating characteristic of the motor and means for detecting the direction in which said second characteristic varies between two preceding successive activations so as to determine the sign of the activation signal injected into the reference signal on the next excitation.
It is thus possible to transmit maximum torque to the driving wheels continuously.
The monitoring apparatus of the invention may also have one or more of the following characteristics, taken in isolation or in any technically possible combination:
with the reference signal being generated on the basis of a third characteristic magnitude of the operation of the motor, the activation stage includes comparator means for comparing the value of said third characteristic with a predetermined threshold value, said means for generating the activation signal causing the amplitude of the activation signal to vary correspondingly as a function of the result of said comparison;
the reference signal is a motor torque reference signal;
the first characteristic is generated on the basis of a measurement of the acceleration of the motor;
the second characteristic is generated on the basis of a measurement of the motor torque; and
the third characteristic is generated on the basis of a measurement of the acceleration of the motor.
The invention also provides a control system for controlling the power supplied to a motor of a motive power unit of an electric rail vehicle set, said control system comprising a power supply circuit for supplying electrical power to the motor, said system further comprising apparatus as defined above for monitoring the adhesion of the motive power unit.